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Concrete protection blocks, Northstar Production Island, Prudhoe Bay, Alaska

Photo: Ben C Gerwick / COWI
Northstar Production Island, Alaska.
COWI MARINE North America was retained by BP Exploration (Alaska), Inc. to perform a feasibility study and detailed design of concrete blocks for protection of the Northstar Production Island.


The scope of the work included an independent investigation to determine primary causes of damage to the existing protection blocks at the site, development of feasible design alternatives that would effectively enhance structural strength and improve performance of the concrete blocks, comparison of design concepts, and cost estimates.

Assessing wave impact

The work included assessment of metocean conditions including frequencies of occurence of waves and ice, wave loads arising from wave breaking, wave slamming, wave uplift, and ice loads resulting from adfreeze, impacts by ice floes and ice bergs as well as impacts from ice chunks driven by wave action.

Conceptual and detailed design

The conceptual and detailed design stages evaluated numerous block designs for varying plan shapes and thickness of blocks in combination with various rebar configurations and concrete strengths.

Comprehensive 2D and 3D finite-element modeling was utilized to evaluate the performance of the block designs.

LAST UPDATED: 07.02.2017